We propose a novel cellular therapy to address the problems of opportunistic viral infection and relapse of B-lineage malignancies after haploidentical stem cell transplantation (Haplo SCT). Viral infections remain a significant cause of failure in patients receiving allogeneic hematopoietic stem cell transplantation (HSCT). Recipients of Haploidentical (Haplo) donor grafts are at particular risk because of the T-cell depletion required to prevent graft versus host disease (GvHD). Antiviral drugs are effective only for some viruses, and most have significant toxicities. Our center has developed a novel approach that effectively expands cytotoxic T lymphocytes (CTL) specific for cytomegalovirus, Epstein-Barr virus and adenoviruses from T- cells in a single culture. Adoptive transfer of these multivirus-specific CTL (MV-CTL) from stem cell donors (including Haplo donors) has proved safe and highly effective in vivo. However, relapse remains a significant problem after Haplo SCT especially for patients with B-cell malignancies. Therefore, we have designed a chimeric antigen receptor (CAR) to redirect antigen specificity of T cells to the B cell lineage-restricted cell- surface molecule CD19. We hypothesize that the incidence of viral infection and relapse following Haplo SCT can be reduced by adoptively transferred donor-derived MV-CTL, genetically modified to be specific for the CD19 molecule expressed by tumor cells. In Aim 1 we will conduct a Phase II randomized clinical trial in which we will give CAR-CD19-1- MV-CTL or no CTL to patients with CD19-I- malignancies who have received a Haplo SCT. In Aim 2, we will delineate; (i) the magnitude and duration of persistence and (ii) the anti-viral and anti-leukemic effects of adoptively transferred CTL. In aggregate, the results of the studies will facilitate the evolution of targeting post-HapIo SCT MRD with viral- and CD19-specific CTLs for enhanced disease- free survival of patients with B cell malignancies. Our proposal is feasible since our center has extensive experience developing, implementing and completing complex biological therapies with cell and gene therapy products and has successfully sponsored and implemented over 40 cell and gene therapy studies under more than 25 investigator initiated INDs, including Phase II multicenter studies .